A 51-year-old Indian man presented with asymptomatic polygonal-shaped dark brown to black-colored macular pigmentation over the zygomatic areas of the face (the right side being more prominent than the left), of 1-year duration. The lesion had ill-defined borders (subtly merging with the surrounding normal skin) and a rough surface with a finely granulated pattern in the center [Figure 1]. The patient denied history of any preceding dermatoses, trauma, local topical application, or any systemic medication. Although his exposure to the sun was limited owing to his indoor occupational habitus, he had still been applying a broad-spectrum sunscreen with sun protection factor 50 twice-a-day daily for the past 5 years. He categorically denied manually rubbing the lesion or using a scrubbing cleanser. He preferred to sleep on the right side of the face. He denied history of any known medical disorder, but reported history of type 2 diabetes mellitus and hypertension in both parents. On general examination, he was detected with central obesity (body mass index = 31.2) and elevated blood pressure (BP = 170/108 mmHg). His hypertensive state was confirmed by daily BP charting. Acanthosis nigricans (AN) in the body folds was conspicuously absent. Videodermoscopy (Escope; 20×) revealed a nonspecific pattern of light brown background, with the presence of multiple scattered brown-colored globules and clods. Characteristically, circular- to oval-shaped brown “rings” were seen with perifollicular accentuation [[Figure 2]a]. Lesional histopathology revealed increased basal layer melanocytes, mild epidermal hyperplasia, and papillomatosis, but no dermal inflammation or amyloid deposits [[Figure 2]b]. Biochemical investigations revealed insulin resistance with overt diabetes mellitus, and hyperlipidemia, thereby confirming the presence of a metabolic syndrome (MS) [Table 1]. Electrocardiogram (ECG) at rest was normal, but exercise stress ECG test suggested myocardial ischemia. A final diagnosis of maturational hyperpigmentation (MH) with MS was made, and the patient was referred to the cardiologist for further management. He was advised to continue using sunscreen and was recommended to locally apply glycolic acid in the form of home-use gel (20%) during the night. However, the patient discontinued its usage within a week.

Figure 1: Hyperpigmented polygonal macular lesion, with a rough texture and granularity in the central portion, over the right zygomatic region of the face in a 51-year-old Indian man

MH, an ill-understood and under-recognized facial melanosis, was described by Dr. A. Melvin Alexander in seven Black individuals.[1] We have also reported a series of 35 Indian patients with MH, of whom 60% were detected with MS.[2] The other probable associations/characteristics of MH observed by Dr. Alexander and reported in our case series include adult onset, obesity, relative lack of local cutaneous symptoms, doubtful relationship with sun exposure, and a prominence of pigmentation over the patient’s preferred sleeping side.[1],[2] The presence of fasting hyperglycemia and hyperinsulinemia in more than 70% of the patients suggests MH as a potential cutaneous marker of MS.[1],[2] MH is easily differentiable clinically and histopathologically from melasma, exogenous ochronosis, lichen planus pigmentosus, Riehl’s melanosis, pigmentary demarcation lines, and postinflammatory hyperpigmentation. Friction melanosis and facial AN comprise the two closest differentials of MH. Excepting the prominence of pigmentation of MH on the individual’s preferred sleeping side, the patients’ denial regarding localized rubbing/scrubbing confidently rules out a tenable role of friction in its pathogenesis. Moreover, Lifa disease or friction melanosis (a condition with significant overlap with cutaneous amyloidosis) has a very different clinical profile and lesional distribution. AN involving the face constitutes the closest differential of MH. However, the dermoscopic findings of facial AN parallel that of flexural AN typified by crista and sulci cutis and hyperpigmented dots; whereas, on dermoscopy, a MH lesion (as in this case) lacks crista and sulci, and demonstrates brown rings that seem to be concentrated around the follicular openings. Histologically features also such as significant basal layer melanization with only slight papillomatosis also do not favour the diagnosis of AN. However, the possibility of MH and AN being a part of a spectrum of cutaneous markers of MS cannot be ruled out at present and mandates further elucidation. This classical clinical picture of MH is being reported to increase awareness among dermatologists regarding this under-recognized and uncharted disorder of facial hyperpigmentation and the need for prompt screening for MS. Apart from the potential metabolic complications, MH is cosmetically bothersome, especially in women. In our limited experience, the use of peeling and depigmenting agents such as glycolic acid (GA) may be effective in improving the pigmentary and textural abnormality of this peculiar facial melanosis.

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